Stitch-forming mechanism for chain-stitch sewing-machines



A. F. FIFIELD. STITCH FORMING MECHANISIVI FOR CHAIN STITCH SEWING MACHINES. APPLICATION FILED FEB. Ih |918.

1 ,3 1 6,022 Patented Sept. 16, 1919.

2 SEETS-SHEET I.

A. A IdlelA. F. FIFIELD. l smcH roRMlNG MecHAmsM Foa cHAm smcH SEWING MACHINES.

l APPLICATION FILED FEB. I1. 1918. 1,316,022, PatentedSept. 16, 1919.

2 SHEETS-SHEET 2.

A TTU/MEV iT sTATEs PATENT oEEioE.

ALBERT F. FIFIELD, 0F NEWARK, NEW JERSEY, ASSIGNOR `lO THE SINGER MANUFAC- i TUBING COMPANY, A CORPORATION 0F NEW JERSEY.

STITCH-FORMING MECHANISM FOR CHAIN-STITCH SEWING-MACHINES.

Specification of Letters Patent. Patented Sept. 16, 1919.

Application led February 11, 1918. Serial No. 216,435.

To all iii/tom t may concern Be it known that I, ALBERT F. FIFIELD, a citizen of the United States, residing at Newark, in the county of Essex and State of New Jersey, have invented certain new and useful improvements in StitcliForm'n Mechanisms for Chain-Stitch Sewingdchines, of which the following is a specification', reference being had therein to the accompanying drawings.

This invention relates, to single chainstitch sewing machines of the well `known rotary looper type disclosed, for example, in the United States patent to Willcox, No. 44,490, of September 27, 1864.

1n machines of this type, as commonly constructed, it is essential to the formation of enchained loops that the work be fed in the direction in which the looper-beak moves when in loop-seizing position, in order that the descending needle may pass in front of both limbs of the previously formed loop held spread hy the looper, whereby the looper -beak may first seize the nascent needle-loop and subsequently pass between the limbs of the previous needle-loop. `These machines, therefore, while well adapted for straight-away sewing in the direction in which the looper-beak moves in seizin a needle-loop, are practically inoperativew en an attempt is made t0 sew while feeding the work in a direction transversely of the plane of rotation of the looper, the reasonbeing that there is no provision for insuring that the needle will descend in front of both limbs of the previously formed needle-loop and that the previous needleloop will be held spread in a position such that the beak of the looper will pass into it as is essential-to the stitch-forming operation.

1n constructing the machine disclosed in my United States Patent No. 1,226,963, of May 22, 1917, which represents an earlier attempt to utilize chain-stitch mechanism` of the rotary looper type in connection with a jogging work-holder, it was found necessary to vibrate the looper-shaft laterally and to make use of a fixed loop-detaining spur,

into engagement with which the limbs of the` previous needle-loop were carried by bodily jogging movements of the looper; the said spur being disposed at the opposite side of the needle-path from Jthe loop-spreading portion of the looper in its loop-seizing stage of movement and serving to position thelimbs of the needle-thread loops uniformly regardless of the position of the last stitch; this mechanism being more fully disclosed in my Patent No. 1,147,386, of July 20, 1915.

Further experiments with my earlier machine have demonstrated that stitch-forming mechanism of the rotary looper type often breaks thread when an attempt is made at high speed operation and it has been ascertained that the thread breakage is often caused by the whipping around in front of the looper-beak of the needle-loop which is cast off by the looper.

An object of the present invention is to improve and simplify the stitch-forming mechanism disclosed in my said Patent No. 1,226,963 by eliminating the loop-detaining spur and the mechanism for producing bodily jogging movements of the looper,

vide a sewing machine having a joggingl work-holder and stitch-forming mechanism of the rotary looper type adapted to form detached groups of fastening stitches when the work-holder is given jogging movements' transversely of the plane of rotation of the looper-beak.

Still further, the invention has for an obj ject to improve stitch-forming mechanism of the class described by overcoming the tendency of the cast-off needle-loops to whip around in front of and be caught by the looper-beak.

Further objects of the invention will ap pear from the following description and claims.

To the attainment of these ends I have provided a looper of the rotary type having a loop-defiecting andspreading wing which. together with the heel of the beak-forming portion of the looper, defines a throat into the bottom of which the loop seizedby the looper is drawn and held spread ifor subsequent entry by the looper-beak after it has sei'zed a new'A needle-loop. 'I have so constructedv and arrangedv the present looper relatively to the looper-shaft and needle that, during the descent of the needle-point below the work, the'bottom of the loopspreading throat in the looper lies well to the side of the needle-path opposite to the side on which the looper-beak lies at this time. Thethroat of the present looper serves, therefore, to position both limbs of the lastV needle-loop in a rearwardly and downwardly inclined position relatively to the needle-path, thus insuring that the descending needle will' pass with certainty in front of both limbs of said previous needleloop, even though the work be fed transversely of the plane of rotation of the looper. In other wordsf' have fixed the looper-shaft in a` position such that the needle-path lies between the axis of rotation of the looper and the point of the looper-beal; at the time when the needle point is piercing-the work and It have s0 arranged the looper-body relatively tothe axis ofthe looper-shaft that the bottom of the loop-spreading throat lies entirely at lthe same side of the needle-path as the axis of thelooper-shaft.

With; this novell relative arrangement of the needle and -looper it is found that, when the work is fed or jogged back-and-forth transversely of the plane of rotation of the looper, the needle will always descend in front ofthe previous loop and that said previous loopfwill be held spread in a position such that the looper will pass the new needle-loop through the previous needleloop.

To control theneedle-loops as they are being drawn up to the work, a device has been provided which bears upon the-substantially concentric outer edge of the beak-forming portionof the looper and detains each castoffneedle-loopy until the point of the looper has advanced; far` enough and the loop has beeny drawn up. short enough to render it impossible-for suchloop to be again caught by the loopcr-beak. This device is particularly useful in combination with the pres- .ent stitch-forming mechanism since the Inv the accompanying drawings, Figure 1 is a rear side elevation of a well known type of button sewing machine in which the invention has been embodied. Fig. 2 is a perspective view of the work-holder mechanism o'f the machine. Fig. 3 is a front end elevation of the stitching and work-holding mechanisms. Fig. 4 is an elevation of the stitching implements similar to Fig. 3 but at the time the needle-point is entering the work. Fig. 5 is a perspective view of the needle, the looper and the stitching thread loops, when the work-holder is shifted toward the standard of the machine. Fig. 3 is a similar view of the parts when the work-holder is shifted toward the end of the work-arm. Figs. 7 and 8 are front end and front side elevations, respectively, of the parts in the position shown in Fig. 5. Figs. 9 and 10 are front end and front side elevations, respectively, of the parts in the position shown in Fig. 6, and Fig. 11 is a detail perspective view of the loop-controlling device shown in Fig. 3.

In the particular embodiment of the invention illustrated, the machine 'frame comprises a base 1 from which rises the hollow standard 2 of the bracket-arm provided with the overhanging tubular portion 3 tern'iinating in the head 4 in which is jonrnaled the reciprocating needle-bar 5 carrying the eyepointed needle G. Extending forwardly from the standard 1 beneath the tubular portion 3 is the work-supporting arm 7 The present machine is provided with a work-clamp and operating` mechanism therefor constructed substantially in accordance with the disclosure of my said Patent No. 1,226,963 and adapted to handle either twoor four-hole buttons. The work-clamp comprises the jogging bar 8 which extends longitudinally of and rests upon the work-arm 7. To the forward end of the bar S is secured the fabric supporting plate 9 uponl which rests the button-clamp comprisingthe opposed button-gripping jaws 10` 10, carried by the spring-pressed arm 11 secured upon the block 12 mounted upon the rearward end of the bar S. The connections for imparting longitudinal movements to the work-clamp comprises the vertical post 13 rigidly sustained by the rearward end olf the bar 8 and embraced by a slotted arm 14 of a rock-lever fulcrumed at 15 to the bracket 15 bolted to the frame. The other arm 1G of the rock-lever carries a roller 17 which enters a suitable ram-slot 1S in the inner face of the usual cam-wheel 19 actuated, in a manner well known, by the mainshaft of the machine. An .adjusting screw 20 is carried by the usual slide-block (not shown) which is adapted to be secured in various positions of adjustment on the post 13 to vary the amplitude of the longitudinal jogging movements of the work-holder.

Acting on the work-holder in a direction transversely of the work-arm 7 is the well known train of mechanism comprising the slide-plate 21 secured to the bar 8 by dowel pins 22 and a screw 22X and carrying the downwardly extending pin 23 connected by a link 24 to one arm 25 of a bellcrank-lever fulcrumed on a pin 26 sustained by the llli Lampes work-arm 7. The other arm 27 of the bellcrank-lever is slotted to receive a headed pin 28 connected to one end of an adjustable link 29, the opposite end of which is freely connected to the lower end of an actuating memberl or lever 3()` fulcrumed on the transverse pin 31 rigidly heldin a socket formed in the bracket 15. Pivoted `to the lever 30 on the transverse pin 32 is a movable follower-element or arm 32 carrying at its upper end a laterally extending pin 33 on which is journaled a roller 34 adapted to enter a suitable cam-slot 35 in the outer face of the feed-wheel 19. The followerelement or arm 32 ofthe lever 30 carries a fulcruni-pin 36 which, when turned by the handle 37 acts throughsuitable mechanism fully described in my said Patent No. 1,226,- 963 to swing the arm 32 about the `pivotal point 31 and withdraw the cam-roll 34 from the cam-slot 35, at the same time shifting the vertical pin 38 at thev upper end of the arm 32 into engagement with the cam-slot 39 in the stationary arm 40 which serves to shift the work-clamp to aposition halfway between the extremes of its jogging movements laterally of the work-arm when .the follower-arm 32` is disengaged from the actuating cam-slot 35. As this mechanism forms a part of the prior art and is not claimed specifically herein, further description thereof is believed to be unnecessary; It may be stated, however, that at the beginning of a stitching cycle, when the present machine is adjusted to sew four-hole `buttons, the cam-roll 34 lies in an inner concentric portion 35 of the cam-slot 35 and prevents movement of the work-clamp transversely of the work-supporting arm while the sam-slot 1S imparts jogging movements to the work-clamp alternately in opposite directions lengthwise of the work-arm to position 'the left-hand pairA of eyes of the four-hole button for reception of fastening a group of fastening stitches. Thus it will be seen that all of the stitch-positioning movements of the work-holder during a complete stitching cycle are `executed longitudinally of the work-arm with the exception of the single movement ofthe workwork-arm 7 is the rotary looper-shaft 41 into the enlarged and socketed end of which is secured the shank 42 of the rotary looper formed with a loop-seizing beak 43 and with the loop-deflectin and -spreading wing 44. Between the hee 45 of the beak-forming portion of the looper and the wing 44 is a throat 46, the bottom of which aords a groove having forward and rearward extremities 47 and 48 serving to spread the forward and rearward limbs a, L, of the needle-loop seized bythe looper.

Referring to Figs. 3, 4, 7 and 9, it will be seen that the axis of the looper-shaft 41 is placed well to the left of the needle-path and, furthermore, that the looper is so shaped and mounted on the looper-shaft that. the extremities 47 and 48 of the loopreceiving and -spreading groove at the bottoni of the throat 46 lie well to the left of the needle-path during the time the needleeye 1s descending below the work. By virtue of this construction and arrangement of parts, the needle 6 is caused to descend, with certainty, in front of both limbs a, b, of the previous needle-loop whether said limbs extend downwardly from a previous stitch shifted rearwardly of the work-arm, as shown in Figs. 7 and 8, or forwardly of the work-arm, as shown in Figs. 9 and 10. The looper-beak will therefore seize the nascent needle-loop and pass it through the previous needle-loop regardless of the fact that the work is shifted transversely of the plane of rotation of the looper; the direction of movement of the looper beak in seizing a needle loop, being considered as a rearward movement. v

A loop-controller 50 is provided for the purpose of preventing the cast-0H needleloop from whipping around in front of the looper-beak 43. In the present embodiment the loop-controller 50 is in the form of a thin flat spring having its upper extremity curved' in conformity to and bearing upon the concentric outei1 edge-portion 51 of the beak-forming portion of the looper. The spring 50 is mounted upon a pin 52 which is.` adjustably held in a socket in the bracketpiece 53 screwed to the work-arm. The spring 50 will retain yielding control of the needle-loops being cast from the looper until the beak of the looper has passed safely beyond the possible range of movement of said loops as they are being drawn up to the work.

Inasmuch as the point of the loop-seizing beak of the present stitch-forming mechanism has an upward component of motion when it seizes the new needle-loop, said beak is inclined slightly toward the axis of rotation of the looper, so that the beak of the looper will lie more nearly at right angles to the needle when seizing a needle-loop than would otherwise be the case. This will be clear from an inspection of Fig. 3 wherein the dottedvcircular arc c concentric and coincident with the edge portion 51 of the looper serves as a reference line indicating the amount of inward dip of the present looper-beak.

In the various figures the arrows indicate the directions in whichthe parts aremoving:

Havingl thus set forth the nature of the invention, what I` claim herein is I. In a sewing machine, in combination, a reciprocatingneedle, a rotary looper-shaft, a looper formed with. a loop-seizing beak and mounted on said? shaft, and means for shifting the work transversely of the plane of rotation of said looper, the axis of rotation of said looper-shaft being displaced from intersecting relation with the needlepath in the direction of movement ofy the looper-beak when seizing'` a needle-loop.

2. Ina sewing machine, in combination, areciprocating needle, a rotary looper-shaft, a looper formed with a loop-seizing beak and mountedr on said shaft, a work-holder, feeding mechanism for imparting stitch-positioning movements to the work-holder in a direction transversely of the plane of rotation of said looper-,the axis of rotation ofv said looper-shaft being displaced from intersecting relation with the needle-p ath in the direction of movement of the looperbeak when seizinga needle-loop.

'3. In aV sewing machine, in combination, stitch-forming mechanism including a reciprocating needle and a rotary looper formed with a loop-seizing beak, a workholder, and feeding mechanism for producing relative stitch-positioning movements between said stitch-forming mechanism and work-holder in opposite directions transversely of the plane of rotation of said looper, the axis of rotation of said loopershaft being displaced from intersecting relation with the needle-path in the direction of movement of the looper-beak when seizing a needle-loop.

4. In a sewing machine, in combination,l

a reciprocating needle, a rotary looper-shaft, a looper carried by. said shaft and formed with a loop-seizing beak and a loop-spreading wing, the axis of rotation of said loopershaft being so arranged relatively to the needle-path and the loop-spreading wing that the limbs of the previous needle-loop are held spread in a position leading downwardly from the last stitch and away from the needle-path in the direction of loopseizing movement of the looper-beak, whereby the needle will pass with certainty at the 'same side of both limbs of the last needleloop and wil-l lie intermediate the beak of the looper when in loop-seizing posltion and the limbs of the previous needle-loop when the work is shifted transversely of the plane of rotation of the looper.

5. In a sewing machine, in combination, a reciprocating needle, a rotary looper-shaft, a looper carried by said looper-shaft and formedl with a loop-seizing beak and loopspreading wing, the axis of rotation of said looper-shaft being so arranged. relatively to the needle-path and the thread-engaging portionsof the looper that the limbs of the previous needle-loop are held spread in a downwardly andV rearwardly inclined direction from the last stitch, whereby the needle will pass in front of the limbs of the last needle-loop when the work is shifted transversely of the plane of rotation of the looper.

6. In. a sewing machine, irn combination, a reciprocating needle, a rotary looper-shaft, a looper carried by said shaft and formed with a loop-seizing beak and a loop-spreading throat, and'feedingrmechanism for shifting the work transversely of the plane of rotationl of the looper-beak, the axis of rotation of said looper-shaft being so arranged relatively to the looper and needlepath that the looper-beakand the bottom of the loop-spreading throat will be disposed at opposite sides of the needle-path at the time the looper-beak is about to seize the nascent needle-loop.

7. In a sewing machine,.in combination, a reciprocating needle, a rotary looper-shaft, a looper mounted on said shaft, said looper having` a loop-seizingbeak and a throat adaptedr to receive and spread a needle-loop seized by the looper, the axis of rotation of the looper-shaft being so arranged relatively to the needle-path and the bottom of said throat that when the beak of the looper is in loop-seizing position the needle-path will lie between the looper-beak and the bottom of said throat.

S. In a sewing machine, in combination, a. reciprocating needle, a rotary looper-shaft, a looper mounted on said shaft, said looper having a loop-seizing beak and a throat adapted to receive and spread a needle-.loop seized`v by the looper, the point of said beak having an inward inclination or dip toward the axis of said looper-shaft and the axis of rotation of the looper-shaft being so ar` ranged relatively to the needle-path and the bottomof said throat that when the beak of the looper is in loop-seizing position the needle-path will lie between the looper-beak and the bottom of said throat.

9. In a sewing machine, in combination, a reciprocating needle, a rotary looper having a loop-seizing beak and a loop-spreading throat and means for shifting the work transversely of the plane of rotation of the looper, the loop-spreading throat of the looper being so positioned and of a width such that the limbs of the previous needle loop are held spread in a downwardly and rearwardly inclined direction from the last stitch and on opposite sides ofthe path ofthe looper beak when the latter is moving rearwardly in loop-seizing position.

l0. Ina sewing machine, in combination, a reciprocating needle, arotary looper having a loop-seizing beak and a loop-spread ing Wing, and a loop-controller cooperating with said looper when in cast-oiiI position to control the needle-loops cast from the loopei` and thereby prevent said loops 'from Whipping around in Jfront of the beak of the loopr when the machine is operated at high s ee p11. In a sewing machine, in combination, a reciprocating needle, a rotary looper having a loop-seizing beak and a loop-spreading Wing, and a loop-controller bearing yield ingly against the outer edge-portion of the loop-seizing beak when the looper is in casto position to control the needle-loops cast from the looper and thereby prevent said loops from Whipping around in front of the beak of the looper When the machine is oper ated at high speed.

12. In a sewing machine, in combination, a recprocatno needle, a rotary looper hav ing a loop-seiz1ng beak and a loop-spreading Wing, and a loop-controlling spring bearing lightly against the looper When in east-off position to control the needle -loops cast from the looper and being drawn up to `the Work and thereby preventing said loops from whipping around in front of the beak of the looper When the machine is operated at high speed.

In testimony whereof, I have signed my name to this specification.

ALBERT F. FIFIELD.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

